1. Field of the Invention
The present invention relates to an information processing apparatus, and more particularly to an information processing apparatus having a plurality of nodes each having at least one CPU and a plurality of multiplex storage devices.
2. Description of the Related Art
In information processing apparatus having a plurality of nodes each having a CPU and a memory and storage devices connected to the nodes, the storage devices are often arranged in a duplex configuration for increased reliability.
Specifically, two storage devices which store the same data are connected to a plurality of nodes, and either one of the storage devices is used in an active system. If the storage device in the active system suffers a fault, then the other storage device switches to the active system, so that any trouble due to the failure of the storage device can be prevented from happening.
However, if either one of the storage devices is subjected to a failure, then the information processing apparatus needs to operate in the absence of a backup system until the repair of the faulty storage device is completed. As a result, the reliability of the information processing apparatus is lowered.
One solution would be to increase the multiplex level of storage devices. In the conventional system which uses the duplex storage devices, when one of the storage devices suffers a fault, the other storage device is simply selected. A multiplex level equal to or higher than a triplex level cannot be achieved simply by expanding the conventional system.
It is therefore an object of the present invention to provide an information processing apparatus having storage devices with an increased multiplex level for higher reliability.
To achieve the above object, there is provided in accordance with the present invention an information processing apparatus having a plurality of nodes each having at least one CPU and multiplex storage devices, comprising memory means associated with each of the CPUs for storing information indicating that each of the multiplex storage devices is either an active system, a backup system, or unconnected, access means for accessing the memory means depending on information stored in the memory means, fault detecting means for detecting when a fault occurs in each of the multiplex storage devices, fault indicating means for indicating the occurrence of a fault to a CPU if the fault detecting means detects the occurrence of the fault and the CPU has accessed the fault indicating means, and updating means for updating information stored in the memory means according to predetermined rules if the fault indicating means has indicated the occurrence of the fault.